lib/Target/BPF/BPFAsmPrinter.cpp

   1 //===-- BPFAsmPrinter.cpp - BPF LLVM assembly writer ----------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains a printer that converts from our internal representation
  10 // of machine-dependent LLVM code to the BPF assembly language.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "BPF.h"
  15 #include "BPFInstrInfo.h"
  16 #include "BPFMCInstLower.h"
  17 #include "BPFTargetMachine.h"
  18 #include "BTFDebug.h"
  19 #include "MCTargetDesc/BPFInstPrinter.h"
  20 #include "TargetInfo/BPFTargetInfo.h"
  21 #include "llvm/CodeGen/AsmPrinter.h"
  22 #include "llvm/CodeGen/MachineConstantPool.h"
  23 #include "llvm/CodeGen/MachineFunctionPass.h"
  24 #include "llvm/CodeGen/MachineInstr.h"
  25 #include "llvm/CodeGen/MachineModuleInfo.h"
  26 #include "llvm/MC/MCAsmInfo.h"
  27 #include "llvm/MC/MCInst.h"
  28 #include "llvm/MC/MCStreamer.h"
  29 #include "llvm/MC/MCSymbol.h"
  30 #include "llvm/Support/TargetRegistry.h"
  31 #include "llvm/Support/raw_ostream.h"
  32 using namespace llvm;
  33
  34 #define DEBUG_TYPE "asm-printer"
  35
  36 namespace {
  37 class BPFAsmPrinter : public AsmPrinter {
  38 public:
  39   explicit BPFAsmPrinter(TargetMachine &TM,
  40                          std::unique_ptr<MCStreamer> Streamer)
  41       : AsmPrinter(TM, std::move(Streamer)), BTF(nullptr) {}
  42
  43   StringRef getPassName() const override { return "BPF Assembly Printer"; }
  44   bool doInitialization(Module &M) override;
  45   void printOperand(const MachineInstr *MI, int OpNum, raw_ostream &O);
  46   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
  47                        const char *ExtraCode, raw_ostream &O) override;
  48   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum,
  49                              const char *ExtraCode, raw_ostream &O) override;
  50
  51   void EmitInstruction(const MachineInstr *MI) override;
  52
  53 private:
  54   BTFDebug *BTF;
  55 };
  56 } // namespace
  57
  58 bool BPFAsmPrinter::doInitialization(Module &M) {
  59   AsmPrinter::doInitialization(M);
  60
  61   // Only emit BTF when debuginfo available.
  62   if (MAI->doesSupportDebugInformation() && !M.debug_compile_units().empty()) {
  63     BTF = new BTFDebug(this);
  64     Handlers.push_back(HandlerInfo(std::unique_ptr<BTFDebug>(BTF), "emit",
  65                                    "Debug Info Emission", "BTF",
  66                                    "BTF Emission"));
  67   }
  68
  69   return false;
  70 }
  71
  72 void BPFAsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
  73                                  raw_ostream &O) {
  74   const MachineOperand &MO = MI->getOperand(OpNum);
  75
  76   switch (MO.getType()) {
  77   case MachineOperand::MO_Register:
  78     O << BPFInstPrinter::getRegisterName(MO.getReg());
  79     break;
  80
  81   case MachineOperand::MO_Immediate:
  82     O << MO.getImm();
  83     break;
  84
  85   case MachineOperand::MO_MachineBasicBlock:
  86     O << *MO.getMBB()->getSymbol();
  87     break;
  88
  89   case MachineOperand::MO_GlobalAddress:
  90     O << *getSymbol(MO.getGlobal());
  91     break;
  92
  93   case MachineOperand::MO_BlockAddress: {
  94     MCSymbol *BA = GetBlockAddressSymbol(MO.getBlockAddress());
  95     O << BA->getName();
  96     break;
  97   }
  98
  99   case MachineOperand::MO_ExternalSymbol:
 100     O << *GetExternalSymbolSymbol(MO.getSymbolName());
 101     break;
 102
 103   case MachineOperand::MO_JumpTableIndex:
 104   case MachineOperand::MO_ConstantPoolIndex:
 105   default:
 106     llvm_unreachable("<unknown operand type>");
 107   }
 108 }
 109
 110 bool BPFAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 111                                     const char *ExtraCode, raw_ostream &O) {
 112   if (ExtraCode && ExtraCode[0])
 113     return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
 114
 115   printOperand(MI, OpNo, O);
 116   return false;
 117 }
 118
 119 bool BPFAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
 120                                           unsigned OpNum, const char *ExtraCode,
 121                                           raw_ostream &O) {
 122   assert(OpNum + 1 < MI->getNumOperands() && "Insufficient operands");
 123   const MachineOperand &BaseMO = MI->getOperand(OpNum);
 124   const MachineOperand &OffsetMO = MI->getOperand(OpNum + 1);
 125   assert(BaseMO.isReg() && "Unexpected base pointer for inline asm memory operand.");
 126   assert(OffsetMO.isImm() && "Unexpected offset for inline asm memory operand.");
 127   int Offset = OffsetMO.getImm();
 128
 129   if (ExtraCode)
 130     return true; // Unknown modifier.
 131
 132   if (Offset < 0)
 133     O << "(" << BPFInstPrinter::getRegisterName(BaseMO.getReg()) << " - " << -Offset << ")";
 134   else
 135     O << "(" << BPFInstPrinter::getRegisterName(BaseMO.getReg()) << " + " << Offset << ")";
 136
 137   return false;
 138 }
 139
 140 void BPFAsmPrinter::EmitInstruction(const MachineInstr *MI) {
 141   MCInst TmpInst;
 142
 143   if (!BTF || !BTF->InstLower(MI, TmpInst)) {
 144     BPFMCInstLower MCInstLowering(OutContext, *this);
 145     MCInstLowering.Lower(MI, TmpInst);
 146   }
 147   EmitToStreamer(*OutStreamer, TmpInst);
 148 }
 149
 150 // Force static initialization.
 151 extern "C" void LLVMInitializeBPFAsmPrinter() {
 152   RegisterAsmPrinter<BPFAsmPrinter> X(getTheBPFleTarget());
 153   RegisterAsmPrinter<BPFAsmPrinter> Y(getTheBPFbeTarget());
 154   RegisterAsmPrinter<BPFAsmPrinter> Z(getTheBPFTarget());
 155 }